Production trees (sometimes referred to as Christmas trees) are typically positioned on a well, both subsea and surface wells, to control the production of hydrocarbon fluids from the well. Such production trees typically include several valves that are selectively actuated to control production of hydrocarbon fluids from the well and to allow access to the well for certain remedial operations, such as injecting chemical into the well, monitoring conditions within the well, relieving pressure from within the well, etc. The production trees are typically classified as either vertical trees or horizontal trees. In a vertical tree, the primary production path is positioned vertically above the wellhead and various valves, e.g., a master valve, a swab valve, are positioned within this vertical production path to control the production of hydrocarbon fluids. In contrast, in a horizontal tree, there are no valves in the vertical bore wherein the hydrocarbon fluids produced are diverted horizontally within the tree to various valves outboard of the vertical bore.
After a well is drilled, certain activities and certain equipment must be installed in the well—i.e., the well must be completed—before production operations can begin. In general, the completion of a well may involve activities such as perforating the well, installing production tubing within the well, installing packers within the well, etc., wherein all of this installed equipment may generally be referred to as the “completion.” Importantly, the well completion is designed and tailored based upon the known parameters of the well, such as the internal formation pressure, at the time the completion is made as well as the anticipated changes in the parameters of the well over the anticipated life of the well. For various reasons, the internal formation pressure of a well may decrease over time as hydrocarbon fluid is continuously produced from the well. In some cases, a well may be shut-in or abandoned if the natural formation pressure falls to a low enough level such that the well no longer produces hydrocarbon fluid at a rate that makes the well economically viable.
In some cases, an electrically submersible pump (ESP) is installed in wells to increase the production of hydrocarbon fluid from a well. In general, an ESP is an “artificial lift” mechanism that is typically positioned relatively deep within the well were it is used to pump the hydrocarbon fluid to the surface. However, installation of an ESP on an existing well can be very expensive for several reasons. First, installation of an ESP on an existing well requires that the completion be pulled and replaced with a completion that is designed for and includes the ESP. Second, such workover operations require the use of expensive vessels (e.g., ships or rigs) to re-complete the well, given the equipment that must be removed from the well during these workover operations. Even in the case where the well initially included an ESP, or where one was later added to the well, such ESPs do malfunction and have to be replaced. Thus, even in this latter situation, expensive vessels must be employed in replacing previously-installed ESPs.
The present application is directed to a unique system for installing an electrically submersible pump (ESP) on a well, such as a subsea well, that may eliminate or at least minimize some of the problems noted above.